(20 U.S.C. 6301 et. seq.), as amended by this Act, from programs. authorized under the Elementary and Secondary Education Act. of 1965 (20 U.S.C. 6301 et seq.), as in effect on the day before. the date of enactment of this Act.
The efficacy of a vaccine is different from its effectiveness. It is dependent on several factors such as: 1  adherence to vaccine schedules. 2  the disease â some diseases have vaccines against them that perform better than for other diseases. 3  the strain of vaccine â some vaccine strains are more effective than others.
More than two centuries have passed since the first successful vaccine for smallpox was developed. We've come a long way since. Today's vaccines are among the 21st century's most successful and cost-effective public health tools for preventing disease and death. Thanks to immunizations, debilitating and often fatal diseases like polio, that were once common, are now only distant memories for most Americans.